Microelectromechanical systems enable integration of both microelectronic circuits and mechanical structures on a single chip or device, thereby significantly lowering fabrication costs and/or chip size. For instance, compared with their bulk piezoelectric counterparts, MEMS ultrasound transducers (MUT) can have applications not possible in conventional bulk piezoelectric devices, e.g., medical imaging, such as intravascular guiding and diagnosis, fingerprint detection, etc. For example, traditional manufacturing methods are ineffective in creating area array interconnection and reduced transducer sizes.
However, MUT devices, as an alternative method for fingerprint detection typically require MUT devices to be manufactured in the resolution of at least 300 dots per inch (dpi) or higher e.g., approximately 85 micrometer (μm) pixel size. Conventional manufacturing process flows, e.g., with traditional polishing and sawing from bulk piezoelectric materials have not been able to achieve required resolutions, whereas a capacitive MUT (CMUT) linear array can provide such resolution. However, CMUT linear arrays are subject to skin condition and sensor contamination, which can deteriorate the accuracy of fingerprint detection devices employing CMUT linear arrays.
It is thus desired to provide integrated piezoelectric MEMS transducers (PMUTs) on integrated circuit (IC) for fingerprint sensing that improve upon these and other deficiencies. The above-described deficiencies are merely intended to provide an overview of some of the problems of conventional implementations, and are not intended to be exhaustive. Other problems with conventional implementations and techniques, and corresponding benefits of the various aspects described herein, may become further apparent upon review of the following description.